University of Hamburg

About: University of Hamburg is a education organization based out in Hamburg, Germany. It is known for research contribution in the topics: Population & Laser. The organization has 45564 authors who have published 89286 publications receiving 2850161 citations. The organization is also known as: Hamburg University.

Culture and Welfare State Policies: Reflections on a Complex Interrelation

Abstract: In comparative welfare state analyses, cross-national differences have often been explained both by the specific profiles of welfare state institutions and the constellations of social actors. However, the way in which cultural differences also contribute to the explanation is often ignored, or at least treated as a more marginal issue. The aim of this article is to reflect on the relationship between culture and welfare state policies, and consider how it might be analysed in a comparative perspective. A theoretical framework for analysis is introduced in which the relationship of culture and welfare state policies is conceptualised as a complex, multi-level relationship which is embedded in the specific context of a particular society and can develop in contradictory ways.

Tuning size and sensing properties in colloidal gold nanostars.

Abstract: Gold nanostars are multibranched nanoparticles with sharp tips, which display extremely interesting plasmonic properties but require optimization. We present a systematic investigation of the influence of different parameters on the size, morphology, and monodispersity of Au nanostars obtained via seeded growth in concentrated solutions of poly(vinylpyrrolidone) in N,N-dimethylformamide. Controlled prereduction of Au(3+) to Au(+) was found to influence monodispersity (narrower plasmon bands), while the [HAuCl(4)]/[seed] molar ratio significantly affects the morphology and tip plasmon resonance frequency. We also varied the size of the seeds (2-30 nm) and found a clear influence on the final nanostar dimensions as well as on the number of spikes, while synthesis temperature notably affects the morphology of the particles, with more rounded morphologies formed above 60 °C. This rounding effect allowed us to confirm the importance of sharp tips on the optical enhancing behavior of these nanoparticles in surface-enhanced raman scattering (SERS). Additionally, the sensitivity toward changes in the local refractive index was found to increase for larger nanostars, though lower figure of merit (FOM) values were obtained because of the larger polydispersity.

Theory of radar imaging of internal waves

Abstract: Radar images taken over ocean areas, in particular, those obtained by the synthetic aperture radar (SAR) onboard the American Seasat satellite in 19781,2, sometimes show features that seem to be surface manifestations of oceanic internal waves3–11. Here I present a theory explaining the large radar signatures of internal waves in which the imaging is attributed to variations in the short-scale surface roughness induced by current variations associated with internal waves.